Really liked The Crown. I went w/ one other person and I got stuck on the top of a 3 tier and he was on the bottom so it would have been nicer if we were closer and 3 tier bunks aren't exactly my personal favorite but everything else was great - good internet on location, facilities were very clean and decent are - could see London Eye from our window - About a 5-7 min walk to a major tube/train station - can't complain for the cheap price.
Best Hostel we stayed at in the UK. Great location - right next to Edinburgh Castle, just above the Grass Market and at the top of the Royal Mile. Rooms were great and came w/ storage locker under every bed (need refundable deposit to use but worth it and you get it back). Only downfall was very poor free internet. Couldn't look up anything because I couldn't get any good service. I'm not from Europe so the internet was my only means of communication/travel info, etc. Otherwise - my favorite!
Great Hostel right near Temple Bar. Feel free to bring in your own food to cook in the kitchen. Internet was good out in the main area but didn't work as well in bedrooms. Would suggest you walk everywhere - it's all in walking distance. Loved Dublin Castle and the Medieval History that is so strong in this city.